Method and apparatus for providing a well bore with a deflected extension



July 14, 1959 R. Q. BUTTOLPH METHOD AND APPARATUS FOR PROVIDING A WELLBORE WITH A DEFLECTED EXTENSION 7 Sheets-Sheet 1 Filed March 17, 1953INVENTOR. Pa /0b Qjazzak);

After/7g July 14, 1959 Filed March 17, 1953 R. METHOD AND APPAR BOREWITH A Q. BUTTOLPH 7 Sheets-Sheet 2 INVENTOR.

July 14, 1959 R Q BUTTOLPH 2,894,722

METHOD AND APP'ARATus FOR PROVIDING A WELL Filed Mrch 17, 1955 BORE WITHA DEFLECTEID EXTENSION 7 Sheets-Sheet 4 INVEN TOR.

After/7g July 14, 1959 R. Q. BUTTOLPH 2,894,722

METHOD AND APPARATUS FOR PROVIDING A WELL BORE WITH A DEFLECTEDEXTENSION Filed March 17, 1953 '7 Sheets-Sheet 5 I I It'zforn ey N R.Q.'BUTTOLPH METHOD AND APPARATUS FOR PROVIDING A WELL July 14, 1959BORE- WITH A DEFLECTED EXTENSION Filed March 17, 1953 7 Sheets-Sheet 6J/forney July 14, 1959 R.

METHOD AND APPAR BORE WITH A Filed Mdroh 17, 1953 Y Q- BUTTOLPH ATUS FORPROVIDING A WELL DEFLECTED EXTENSION 7 Sheets-Sheet 7 Afro/we UnitedStates Patent METHOD LAND APPARATUS FOR PROVIDING A WELL BORE WITH ADEFLECTED EX'IENSION Ralph Q. Buttolph, Whittier, Calif. ApplicationMarch '17, 1953, Serial No. 342,788 19 Claims. (Ci. 255--1.6)

This invention relates to a method and apparatus for providing a wellbore with an extension deflected rela tive to that bore, and it is ageneral object of the invention to provide a method and apparatus bywhich a well bore can be deflected, say, for example, eitherstraightened or inclined in a predetermined manner Without resort tohazardous mechanisms or practices and in an effective and practicalmanner.

This application is filed as a continuation in part of my applicationentitled Method and Apparatus for Providing a Well Bore With a DeflectedExtension, Serial No. 186,341, filed September 23, 1950, now abandoned.

There are various occasions during the drilling of wells, for exampleoil wells, when a well bore reaches a point from which it is desired toestablish an extension or continuation of the bore inclined or at anangle to the part initially established. Such an operation may involvestraightening a bore that has become deflected from the true vertical,or it may involve leading the bore off or away from the vertical and,possibly, in a predetermined direction therefrom.

The deflecting of Well bores has been accomplished by various methodsand by the use of various devices. It is most common that suchoperations be performed with the aid of large, cumbersome, expensivedevices known as whipstocks or that they be carried out with drillingstrings in which there are pivoted joints, while in other casescombinations of such equipment are employed. It has also been proposedto equip the drill string with an abutment for deflecting it to one sideof the bore, but such structure has not proved practical.

It is well recognized, generally, that methods and equipment such ashave heretofore been used for the operations above mentioned have beenexpensive, have required several and often expensive round trips ofequipment, are not altogether dependable or reliable, and if carried outwith any degree of accuracy they involve or require various timeconsuming and expensive surveying operations, and in most cases requiresuccessive use of various different tools that are heavy, cumbersome andexpensive.

It is a general object of this invention to provide a method to beemployed in the drilling of a Well bore by which a bore that has beeninitially drilled to a given point, or in a given manner, can beextended or continued in a different direction so that there is anextended portion that is deflected from the initial bore, all withoutthe use of or resort to dangerous complicated or highly expensive toolsor equipment.

It is another object of the invention to provide a method of the generalcharacter referred to which is such as to include certain operationsserving to check or verify the action, with the result thatpredetermined deflection of the bore if not initially accomplished asintended can be gained with accuracy and certainty.

It is another object of the invention to provide a method of the generalcharacter referred to by which deflection of a well bore is gained byfirst establishing a pitched counterbore of limited size at the bottomof the well bore, then without replacement of the counterboringequipment proceeding to establish a large extension of the bore whichmay be the size of the bore, or substantially that.

A further object of the invention is to provide a method of the generalcharacter referred to which provides for the drilling of a counterboreat the bottom of a well bore and pitched relative thereto, the extendingof that counterbore and the continuing from the extension with a secondextension pitched relative to the first extension, all with drillingequipment that remains at the well serving to perform the severaldilferent operations mentioned.

Another object of the invention is to provide apparatus for carrying outthe method hereinabove referred to, which apparatus involves few simplepractical parts that are inexpensive of manufacture, convenient tohandle or transport, and which are such that they can be operatedproperly and accurately without the'exercise of unusual or great care.The apparatus provided by the present invention is compact, limited asto size and weight and is such that one unit supplemented by ordinarystandard unit of equipment will drill or perform through a large rangeof hole sizes.

It is another object of the present invention to provide apparatus ofthe general character referred to which eliminates from the deflectingof the Well bore the hazards, uncertainties, and various otherdisagreeable and costly features that commonly attend apparatus providedfor the purpose stated.

It is a further object of this invention to provide apparatus of thegeneral character referred to in which boring equipment is providedinvolving, generally, a drill string, a bit, and a shoe, which elementsare related so that the shoe guides the bit by a wedging action andremains in a given rotative position in the well bore and advances inthe bore as the bit operates, all without the severe working of partssuch as occurs when knuckle joints, or the like, are employed, andwithout operation of the cutters of the bit against a hard metal face,such as occurs when a whipstock is employed to drill out at the side ofa well bore. With the structure of the present invention the bitoperates smoothly and efliciently, always advancing the well bore, andit is not subject to undue wear as by working against or rubbing on adeflecting wedge or the like.

Another object of the invention is to provide apparatus of the generalcharacter referred to wherein an instrument is combined or cooperateswith a drilling tool and guide, to the end that readings or records canbe obtained as desired, for the purpose of accurately locating the guidein the well bore so that the deflected bore is directed in the desiredmanner.

It is a further object of the invention to provide apparatus of thegeneral character referred to wherein the instrument employed is socombined with the equipment provided for drilling as to make possiblecertain checks to assure readings or records which are accurate.

It is a general object of the invention to provide a simple, compact,practical tool characterized by a bit and a guide shoe permanentlyrotatively related thereto, which alone will advance a well bore with ahole of limited size and which, supplemented by a few simple standardelements of drilling equipment, will make possible extension of a largewell bore with a hole of the same size. I

It is .a further object of the invention to provide well deflectingapparatus, that is, a bit and a combined deflecting device, which aresuch that as a unit they are easily and freely operable in the ordinaryWell bore at the bottom thereof where deflection of the bore is desired.The structure provided by the invention is such that there is little orno danger of it becoming wedged or stuck in an ordinary well bore and itis unnecessary to employ reamers or other like equipment to insure itsproper introduction into an ordinary well. In the case of most equipmentemployed for deflecting a well bore, for example, in the case ofwhipstocking equipment, the equipment necessary is large and cumbersomeand is ordinarily just enough smaller than the bore to permitinstallation, all of which commonly results in complications that arecompletely avoided or eliminated by the present invention.

It is a further object of this invention to provide a device fordeflecting a well bore characterized by a bit and a deflecting elementor shoe, which parts are permanently coupled and the structure is freeof temporary or undependable features of construction such as shearpins, or the like.

It is a further object of this invention to provide apparatus of thegeneral character referred to, serving to deflect a well bore byproceeding downwardly from the bottom thereof, as distinguished fromequipment that is intended to gain deflection by cutting away a side ofthe bore such, for instance, as is the case when a whipstock isemployed.

It is another object of this invention to provide apparatus fordeflecting a well bore by means of a wedging device or shoe applied toor arranged adjacent the drilling element or bit and serving to continueor advance as the bit proceeds thereby maintaining constant and uniformwedging action at the bit to the end that constant deflection ismaintained, as distinguished from the limited deflection that isincidental to the use "of a whipstock where the bit is deflected by thewhipstock and proceeds beyond or past it.

It is a further object of this invention to provide well deflectingapparatus of the general character referred to, whereby the desireddeflection is gained by elements acting at the point where drillingoccurs, that is, at the bit and without dependence upon bending orflexure of the drilling string above the bit.

It is a further object of this invention to provide well deflectingapparatus of the general character referred to, characterized by a bitand a guide element permanently coupled to the bit, which guide elementis related to the bit and to the operating string so that it can bereadily oriented in the well bore and will thereafter remain oriented orin a predetermined rotative position in the bore while the bit proceedsto drill and said element goes forward with the bit.

It is a further object of this invention to provide bore deflectingapparatus practical and serviceable in a typical well bore to establishor drill one or more branches or lateral extensions, such as arecommonly referred to as drain holes. With the apparatus of the presentinvention, an extension of a well bore in the form of a drain hole canbe not only started away from the well bore but will continue away fromthe well bore at a predetermined rate and in a predetermined directionso long as the defleeting operation is continued, and because of thewedging action gained by the apparatus, a gradually curved drain holemay be formed ideal for draining of fluid into the well here.

The various objects and features of my invention will be fullyunderstood from the following detailed description of a typicalpreferred manner of carrying out the method and of a typical preferredform of apparatus of my invention, throughout which descriptionreference is made to the accompanying drawings, in which:

Sheet 1 of the drawings illustrates, somewhat diagrammatically, thevarious possible steps employed in the course of a simple carrying outof the invention, Fig. 1 being a view illustrating the establishment ofthe seat or counterbore at the bottom of the initially formed well bore,which operation is performed by the use of the drill string and bitlater used in carrying out the other steps of the method. Fig. 2 showsthe drill string elevated to position the bit well above the bottom ofthe bore and shows the surveying instrument with a portion dependingfrom the bit and into the open well bore. Fig. 3 is a view showing theshoe related to the bit oriented in the desired manner and seated in theseat or counterbore established as shown in Fig. 1. Fig. 4 is a viewillustrating the progress of the drilling operation which establishesthe desired extension of the well bore and serves to illus trate themanner in which such extension may be at an angle relative to theinitial bore and illustrates the manner in which the guide shoecontinues into the extension with the advance of the bit, and Fig. 5 isa view of the bore, being enlarged so that the extension is brought to asize corresponding to that of the initial here, which operation may ormay not be performed, as circumstances require.

Fig. 6 is an enlarged vertical sectional view of the structure providedby the present invention, showing the lower end of a drill string havinga bit mounted thereon through a sub, which sub forms a part of themounting means which carries the guide shoe, the sleeve that supportsthe guide shoe being shown in a down position relative to the sub. Fig.7 is a view illustrating certain of the parts shown in Fig. 6 andshowing a different positioning of the parts, and showing the sleevethat carries the guide shoe adjusted or mounted in an elevated positionon the sub. Fig. 8 is an enlarged detailed transverse sectional viewtaken as indicated by line 8-8 on Fig. 6. Fig. 9 is an enlarged detailedtransverse sectional view taken as indicated by line 9-9 on Fig. 7. Fig.10 is a side elevation of a portion of the structure taken as indicatedby line l0-lil on Fig. 6. Fig. l1 is a transverse sectional view takenas indicated by line 11-11 on Fig. 6. Fig. 12 is an enlarged detailedsectional view taken as indicated by line 12-12 on Fig. 6. Fig. 13 is anenlarged detailed sectional view of a portion of the structure shown inFigs. 6 and 7, illustrating the surveying instrument in operatingposition with reference to the other parts and partly in section to showcertain essential parts thereof. Fig. 14 is a transverse sectional viewtaken as indicated by line 14-14 on Fig. 13. Fig. 15 is an enlargedvertical section taken as indicated by line ll5l5 on Fig. 14. Figs. 16,17 and 18 are views illustrating the type of readings or recordsobtained by use of the surveying instrument, and Fig. 19 is anelevational view showing the particular relationship of the bit and theshoe.

Figs. 20 to 24, inclusive, occurring on Sheet 5 of the drawings,illustrate an embodiment of the invention differing somewhat from thestructure illustrated in Figs. 1 to 19, inclusive. Fig. 20 is similar toFig. 1, except that the structure includes a hole opening tool. Fig. 21is a view similar to Fig. 2 showing use of the equipment illustrated inFig. 20. Fig. 22 is a view similar to Fig. 3 showing use of theequipment shown in Fig. 20. Fig. 23 is a view similar to Fig. 4illustrating use of the equipment illustrated in Fig. 20, and Fig. 24 isa view illustrating use of the equipment shown in Fig. 5.

Another carrying out of the invention is illustrated in Figs. 25 to 27,inclusive, occurring on Sheet 7 of the drawings. In this case, Fig. 25illustrates a continuation of a well bore in a particular manner, andFig. 26 illustrates the use of equipment to ascertain the relationshipof bore extension and the original bore, and Fig. 27 is a viewillustrating the establishment of a second extension at an angle to thefirst to effect a correction or a deviation from the first extension ofthe bore.

The present invention can be used to advantage in a wide variety ofsituations and for the purpose of performing various operations. Sincethe invention is particularly practical as applied to the deflection ofa well bore, either for the purpose of extending a bore dovmwardly forthe purpose of correcting a bore that is angularly related to thevertical or for side tracking an obstacle in a bore, it will bedescribed in such a situation.

Further, since the invention can be carried out to advantage with moreor less conventional well drilling equipment, and by followingconventional rotary drilling practice, it will be described generally inthis connection.

The structure or apparatus provided by the present invention involves,generally, a well drilling string S and a drill head or bit A carried oroperated by means of the string S. A shoe or guide B is cooperativelyrelated to the bit A and may be advantageously carried by a mountingmeans C that involves a tubular sub connecting the bit A and string S,and a sleeve 11 carried by the sub and supporting the shoe. A means Dreleasably locks the shoe B in a predetermined position with referenceto the string S and in a preferred arrangement it is a fluid pressureactuated means acting between the sub 10 and sleeve 11. An instrument E,in the general nature of a well surveying instrument, is operablethrough the string S and into cooperative relationship with the tool atthe lower end of the string and which is formed, generally, by the bit,the shoe, the suband the sleeve. A stop means F operates to checkmovement or descent of the instrument to operating position in the eventthat the means D is released, in which case the shoe may be in anindeterminate rotative position with reference to the string. Further, ameans G indicates, and preferably records, improper positioning of theinstrument E in the tool at the time the instrument operates and thusprovides the operator at the head of the well with a check onperformance.

The string S, which is the operating string that extends into the wellbore W from the upper end thereof, may be of conventional constructionor formation, that is, it may be made up of stands of drill pipeincluding a kelly at its upper end and a drill collar, if necessary, atits lower end. Essentially, however, and insofar as the presentinvention is concerned, it is an elongate tubular element with anopening 12 through it from one end to the other suliiciently large tofreely pass the instrument E, and a line L, such as a cable, which mayserve as a means for handling the instrument.

The bit A may, in practice, vary widely in form and construction,depending upon various factors such as the service to be performed, theformation to be drilled, etc. In the particular case illustrated the bitis shown as involving a body 15 with depending legs 16 carrying rotatingcutters 17. The particular bit disclosed is of a type commonly used inthe drilling of wells, and its various details of construction and itsmode of operation are well understood by those skilled in the art. InFig. 6 the cutters are shown formed to cut a limited or minimum amountof clearance for the body of the bit, whereas in Fig. 19 the cutters areshown such as to cut a substantial amount of clearance.

The shoe B, as provided by the present invention, is an elementengageable with the formation, for instance, in a counterbore 20continuing from the bottom 21 of the well bore W, and in the caseillustrated it is shown as an elongate part disposed, generally, in thedirection of the longitudinal axis of the tool, and it is located at theexterior of the bit A, preferably at the upper portion thereof, where itis confined to one side of the bit and has its lower end terminatingabove the lower end of the bit. The particular shoe shown in thedrawings is arcuate or segmental in cross sectional configuration. Ithas a cylindrically curved exterior guide surface 23 and a cylindricallycurved interior 24, which parts or surfaces, in a general way, fitaround the upper end portion of the bit A, for instance, that portion ofthe bit where the legs join the body and continue part way around thebit, say for instance, through about 120 degrees, as shown in Fig. 11 ofthe drawings. The surfaces 23 and 24 are preferably of about the sameradius of curvature.

The center of curvature of the inside surface 24 of the shoe iscoincidental with the central axis of the bit .at a point even with thebottom of the bit.

6 and :surface 24 "fits the exterior of the bit, the outermost parts ofthe legs 16 or the body 15 with working clearance .or it may havesliding engagement therewith so the bit bears .against the shoe.

In accordance with the preferred form of the invention the exteriorguide surface 23 of the shoe, though cylindrically curved, is formed sothat its center of curvature axis, though close to the center of thebit, is not coincidental with or parallel to the central axis of thetool or bit, but, rather, is inclined somewhat relative thereto. Theaxis of the exterior guide surface extends down and inward relative tothe longitudinal axis of the bit and preferably intersects that axis ofthe bit In Fig. 6 of the drawings, the dotted line X indicates thecentral longitudinal axis of the toll or bit while the dotted line Yindicates the axis of curvature of the exterior guide surface 23 of theshoe.

The shoe B includes, in addition to the features above noted, one ormore stops or keys 30 (see Fig. 11) which serve to check or preventturning of the shoe in a bore or opening in which the shoe is seated,as, for instance, the turning of the shoe in a seat opening 20 or in acontinuation thereof, such as is established by operation of the bit aswill be hereinafter described.

In the particular case illustrated, there are two keys .30 and these arelocated at the vertical edges or edge portion of the shoe where theyproject outwardly or away from the guide surface 23 and extend from oneend of the shoe to the other, parallel with the axis Y about which guidesurface 23 is formed. In the preferred form of the invention the keys 30have sharpened outer edges 31, and their lower ends are sharp andpitched to extend somewhat upward and inward toward each other (see Fig.10). The keys are preferably surfaced or provided with hard facing 32,so that they readily peel grooves out of the formation being drilled andthus act as grips that elfectively prevent turning of the shoe as thebit rotates relative to the shoe in the course of drilling, as will behereinafter described.

The mounting means C formed essentially by the sub 10 and sleeve 11serves to support the shoe B in the desired manner with reference to thebit A, as shown throughout the drawings. The sub 10 is an elongatetubular element which may be considered as a continuation or extensionof the string S, or as an upwardly projecting part of the bit. The subis rigidly connected or coupled to the lower end of the string S, as bya suitable threaded connection, and the bit A is mounted on or carriedby the lower end of the sub through a suitable threaded connection. Inthe case illustrated in the drawings the sub has a socket opening 35entering it from its upper end and a pin 36 on the lower end of thestring is engaged in this socket. A socket opening 37 enters the subfrom its lower end and a pin 38 on the upper end of the bit body 15 iscarried in the socket 37.

The sub 10, being tubular, has an opening or passage through it from oneend to the other, and in accordance with the present invention the upperend portion 40 of this opening or passage is considerably smaller indiameter than the lower end portion 41 which is of substantial size andwhich is in the nature of a cylinder opening. The upper portion 49 ofthe sub opening is preferably round in cross section and of such size asto pass the instrunient E with suitable working clearance. The lowercylindrical opening 41 of the sub extends upwardly into the sub from thesocket 37 and carries various other parts of the structure, as will behereinafter described.

The exterior of the sub is round in cross section, being preferablyturned, and is of substantially uniform diameter except at the lower endportion of the sub where there'is an enlargement or stop 43 presentingan upwardly facing stop shoulder 44. The extreme upper end portion 45 ofthe exterior of the sub is somewhat smaller 7 than the portion 46adjoining the stop 43, and there is a threaded portion 47 between theportions 45 and 46.

The sleeve 11 of the mounting means C is carried on the portion 46 ofthe sub 10 where it is held or confined by the stop 43 and a stop 48threaded onto the part 47, so that it does not shift vertically orlengthwise of the string and bit. The sleeve 11 is held on the sub sothat it is freely rotatable thereon and it is preferably confined by thestops so that it does not shift axially of the sub. Sleeve 11 is fittedupon the sub so that no appreciable movement radially (or transversely)of the longitudinal axis of the tool may occur. Thus, the external orguiding surface of shoe B is definitely located in a fixed axial andradial relationship to the axis of rotation of the bit or, in morepractical terms, the shoe may move relative to the bit only in rotation.The sleeve may, if it is so desired, be mounted so it is adjustable orvariable axially of the sub in order to vary the position of the shoelengthwise or vertically of the bit. By varying the vertical position ofthe shoe relative to the bit, the deflecting or bit guiding action ofthe shoe is varied. In the preferred setting or relating of parts thelower end of the shoe is positioned somewhat above the lower end of thebit. In the particular case illustrated, one or more inserts 50 may beprovided between the stops 43 and 48 and it will be apparent that byvarying the size and arrangement of such stops the position of thesleeve can be varied, as desired. In Fig. 6 of the drawings, I show asingle insert 50 arranged between the upper end of the sleeve and thestop 48, with the result that the sleeve is in its lowermost position.In Fig. 7 I show the other extreme positioning of the sleeve broughtabout by locating the insert 50 between the lower end of the sleeve andthe stop 43.

In the preferred construction wear-taking rings or bearings 51 areprovided on or as a part of the upper end of sleeve Ill and on collar43, as this portion of the sleeve rubs or wears against either the stop48 or insert 50 as the tool is operated to bore.

In the preferred form of the invention the shoe B hereinabove describedis mounted directly on or is joined to the sleeve Ill, as an integralpart or continuation thereof, this preferred construction being shownthroughout the drawings. In the particular case illustrated, the sleeve11 has a skirt portion 11 which depends from the part carried on theportion 46 of the sub and surrounds the stop 43 as clearly illustratedin Figs. 6 and 7 of the drawings.

The lock means D serves primarily as a releasable lock between the shoeB and the string S fixing these parts against relative rotation and withthe shoe in a predetermined rotative position relative to the string, orto the sub 10 which is, in eflect, a part of the string. In the form ofthe invention illustrated the lock means D is provided or is locatedbetween the sub 10 and sleeve 11 and it includes a lock dog or bolt 61operated by a core 67 operable in the sub 10. The bolt is operable intoand out of an opening 62 provided in the sleeve 11. The core 67 is apart of an actuating means for the bolt 61, which actuating means ispreferably a fluid pressure actuated structure.

The bolt 61 in the case illustrated is round in cross section and isslidably carried in a bore 65 formed radially in the sub 10 at a pointwhere the sub is surrounded by the sleeve 11. A suitable fluid pressureseal 66 is carried by the bolt and seals the bolt in the opening 65. Theopening 62 provided in the sleeve 11 to receive the bolt is shown asformed completely through the sleeve, and it is of such length as toreceive the bolt when the sleeve is set in various positions lengthwiseof the sub.

In accordance with the present invention the bolt is located at aparticular point around the sub, as related to other parts of themechanism, and the opening 62 is located in a particular manner withreference to the shoe so that when the bolt is engaged in the opening 62locking the sleeve against rotation on the sub, the shoe is in apredetermined rotative position with reference to the string S.

The actuating means for the bolt 61 involves the core 67 which isslidably carried in the cylindrical portion 41 of the passage providedthrough the sub 10. The core 67 is normally yieldingly held in an upposition by a helical compression spring 68 that engages the lower endof the core and is seated on the upper end of a rest 143 seated on thepin 33 of the bit. A stop 69 limits upward movement or travel of thecore 67 and is shown as an extension of a lock pin 70 which locks thestop 48 on the sub 1%. The core 67 is a plunger or piston-like elementsubject to reciprocation in the sub and it is provided with a centralpassage 71 which extends through it from one end to the other. Thepassage 71 in the core is preferably such as to pass the instrument E,as does the opening 40 in the sub.

In accordance with the present invention a flow actuated check or chokeis preferably provided in connection with the core to retard downwardflow of fluid through the core so that such flow of fluid operates thecore downwardly in the sub against the resistance of the spring 68.Checking of fluid will result from an opening 71 of limited size or itmay be gained by a choke. In the particular case illustrated the chokeis in the form of a pivoted closure 89 carried on a pivot pin 81 so thatit is located at the upper end of the core. The closure is normallyyieldingly held up by a suitable spring 32 and in its normal openposition it extends up and somewhat inwardly so that when fluid flowsdownwardly in the sub it catches the closure and swings it from theposition shown in Pig. 6 to that shown in Fig. 7.

The closure 86 does not completely stop flow through the structure sinceit has a flow passage 83 through it. The passage 83 is considerablysmaller than the passage 71 in the core and thus serves to set upresistance to the passage of fluid which results in downward move mentof the core from the position shown in Fig. 6 to that shown in Fig. 7when fluid is circulated downward through the tool.

The bolt 61 is suitably coupled with the core 67 so that as the coreshifts or operates in the sub the bolt is operated between the positionsshown in Figs. 6 and 7. In the particular case illustrated, alongitudinal channel $4 is provided in the exterior of the core and hasinclined or pitched guideways 85 in its opposed walls. A tongue 86projects from the inner end of the bolt 61 into the channel 34 andcarries a coupling member, preferably a ball 87, which operates in theguideways 85. The guideways are inclined or pitched relative to thelongitudinal axis of the structure so that when the core 67 is up, asshown in Fig. 6, the bolt is in operating position or extended so thatit is engaged in the opening 62 locking the sleeve against rotation onthe sub. When the core 67 is down, as shown in Fig. 7, the bolt 61 isretracted or is free of opening 62 allowing the sleeve to rotate freelyon the sub.

The instrument E, as employed in carrying out the present invention, maybe varied widely. However, it is preferably of the general type commonlyknown as or referred to as a single shot, being an instrument operablethrough the drilling string S, and to and possibly through the assemblyof parts or tool occuring on the lower end of the string S.

In the particular case illustrated the instrument E involves, as shownin Fig. 13, an elongate tubular case 9% closed at both ends and when itis in operating position with reference to the tool on the lower end ofthe string S, it has a lower portion 91 that depends a substantialdistance below the bit, as shown in Pig. 2 of the drawings. Within thisdepending portion of the case there is a direction indicator which maybe a magnetic needle 92, and it is preferred, also, to provide aninclination indicator which may be in the form of a plumb bob 93. Arecorder 94, preferably a suitably time controlled photographic unit, iscarried in the case and is related to the indicators 92 and 93 so thattheir actions are suitably recorded in the manner common to instrumentsof this general character. A marker or indicator 130 is provided in afixed position in the case so its image or position is recorded with theother data.

From the foregoing description and from the drawings, it will beapparent how the case of the instrument passes through the sub 10, thecore 67 and to and through the body of the bit A. The bit employed incarrying out the invention is preferably of the type com- .monly termeda trigger or trap door" bit, being a bit wherein there is a largevertical opening through the bit, and at the center of the structurethere is pivoted central cutter 96, as indicated in Fig. 6 of thedrawings. This structure serves to pass the case of the instrument inthe manner shown in Fig. 13. Cutter 96 normally projects across theopening that passes the instrument and serves to cut away the core leftby the cutters 17. This type of bit is illustrated in United StatesLetters Patent No. 2,179,010, issued November 7, 1939.

In accordance with the present invention a suitable stop means isprovided for limiting downward passage or movement of the instrumentrelative to the tool on the lower end of string S. In the caseillustrated an enlargement or stop 100 is provided on the exterior ofthe case at the upper portion thereof and engages a stop shoulder 101provided in the sub 10 at the upper end portion thereof.

In practice it is convenient to handle or operate the instrument E bymeans of a line L and under normal operating conditions it is merelynecessary to lower the instrument by means of the line until theinstrument is stopped in the position shown in Figs. 2- and 13 of thedrawings.

In accordance with the present invention the instrument E, as abovedescribed, is cooperatively related to the tool at the lower end of thestring S, and more specifically with the shoe B, so that the operatorcan ascertain the rotative position of the shoe. For this purpose theinstrument includes one or more indicators. In the present case I showindicators in the form of two magnetic elements or needles 110 and 111which may be mounted one above the other on a central vertical pivot112. These needles are alike and each has one end 113 pointed and theother end in the form of a tail 114. Being like magnetically the needlesnormally assume a position where the point end of one overlies the tailend of the other in a manner such as is shown in the record illustratedin Fig. 16 of the drawings.

The present invention provides one or more actuators, such as magnets M,in the tool, preferably in the upper end portion of the sub. The magnetsare preferably located diametrically opposite each other and one has itspositive pole innermost while the other has its negative pole innermost.The magnetic needles 110 and 111 are so located in the instrument E asto occur opposite the magnets M when the instrument is properly locatedor seated, as shown in Fig. 13. The magnets M, being considerablystronger magnetically, than the needles, immediately position theneedles so that their positions coincide or, in other words, so that thepointed ends are in register and the tail ends are also in register, asshown in Figs. 14, 17 and 18 of the drawings.

In connection with the needles 110 and 111 I may provide an inclinationindicator such as a gravity actuated ball 120 on a convex surface, or aplumb bob 121, or both. The instrument E further includes means, such asa photographic unit 122, which may be time controlled and which servesto make arecord of the needles 110 and 111, as well as theindicators 120and 121. A further in- '10' dicator is provided in the form of aprojection 130in the case, which makes a record of the rotative positionof the case in the tool at the time the various records are made by theinstrument. Indicators 130 and 130 are in line vertically.

In accordance with the present invention the magnets M are in apredetermined rotative position with reference to the lock means D andconsequently with reference to the shoe B, and it is through this knownrelationship of parts that the readings obtained from or through theinstrument E, upon its being withdrawn from the drill string followingactuation, can be observed or interpreted to enable the operator to knowthe rotative position of the shoe B in the bore at the time theinstrument E is operated.

As a result of the structure just described, when theinstrument E makesa record having its lower end portion properly depending from the bit A,the recording includes a record of the needles and 111 showing theseneedles coincidental, as shown in Figs. 14, 17 and 18. However, shouldthe instrument be in other than the proper position the recording orreading obtained will show the needles 110 and 111 oppositely related,as shown in Fig. 16 of the drawings.

From the foregoing description it will be apparent how the instrument Ecan be rapidly lowered to operating position by means of the line L andthrough proper setting or timing of the instrument records are made asby the photographic units 94 and 122, the unit 94 recording theinclination and rotative position as by reference to the earthsmagnetism, while the unit 122 records the rotative position of the tool.With these factors known or recorded the operator can either leave the.string S in the position at which the records were made, if thatposition is satisfactory, or the strings can be rotated the desiredamount to bring the shoe to the desired rotative position, all as wll bedescribed in the following description of operation. Information fromunit 94 is relayed to unit 122 through indicators and 130.

The stop means F, provided by the present invention, is pnovided as ameans: that positively stops or positions the instrument E in thelocation shown in Fig. 13 at a time when the means D is released so thatthe shoe B is not necessarily in a given rotative position withreference to the magnets M or string S. The stop means F is shown asincluding a stop member operable into and out of the passage thatextends through the tool to pass the instrument. The stop member 140 ispreferably a pivoted member carried on a pivot pin 141 mounted in arecess 142 provided in the core 67. The pivoted stop member 140 normallyhangs or depends in a position clear of the passage through the tool.

An actuator 143 is provided to operate or actuate the stop member 140into the passage or into the path of the instrument E when the core 67is in other than its uppermost position. The actuator, as shown in thedrawings, is in the form of an extension or seat 143 above the upper endof the pin 38. The seat has an inclined operating shoulder 144 whichengages the pivoted member 149. When the core 67 is lowered from itsuppermost position the inclined shoulder 144 causes the member 140 to beswung inwardly and finally to a position such as is shown in Fig. 7.Inward movement of the member 145) fromthe position shown in Fig. 6,even though slight, will stop passage of the instrument downward to theproper operating position and, therefore, unless the core 67 is up, inwhich position the bolt 61 is engaged in the opening 62, the instrumentcannot be passed downward to the position shown in Fig. 13.

In employing the structure or apparatus that I have provided and incarrying out the method of the present invention, an operating string Swith the tool on its lower end is first lowered into the well bore W,that is, into the bore 205, and is operated to form the seat orcounterbore 20 extending from the bottom of bore 205, as shown ill inFig. 1. It is to be understood that the sub l0, sleeve 11, shoe B andbit A form an assembly on the lower end of the string S that can beconveniently referred to as a tool. The seat opening or counterbore 20can be drilled, prior to orienting the tool, to a suitable depth such asis illustrated in Fig. 1. If fluid is circulated down through the stringS the core 67 will be lowered and the shoe released relative to the bitso that the bit operates with out carrying or dragging the shoe aroundwith it. However, if fluid is not circulated the shoe will be carriedaround with the bit as the counterbore is drilled.

When a suitable seat or counterbore has been established circulation offluid is stopped and the string rotated slightly causing the sub to turnwithin the sleeve until the bolt 61 registers with the opening 62,whereupon the spring 63 will elevate the core 67, causing the bolt to beengaged in the opening 62. The shoe is now locked in a predeterminedrotative position with reference to the magnets M carried by the sub,and therefore with reference to the string S. The string is thenelevated to move the bit to a position well above the bottom of thebore, as shown in Pig. 2.

The line L is then operated in the string S to lower the instrument Einto the position shown in Fig. 13, in which position the lower endportion 91 of the instrument case depends a substantialy distance belowthe bit and into the open well bore, so that the action of the needle 92is not impaired by the presence of the bit and other parts above it.

The instrument E, which is magnetically influenced is then operated, asby means of a timer or by a suitable wired control or through othercontrol means, recording the positions of the various indicatorsincluded in the instrument, particularly the indicators 92, 110 and 111.If it is important to ascertain inclination, then the recordings of theindicators 93, 12d and 121 may be important.

Without rotating the string 5, or after its position has been recorded,the instrument E is Withdrawn and the recordings made by the instrumentare read or interpreted, with the result that the operator is advised asto the rotative position of the shoe in the well. With this knowledgethe operator can leave the shoe in the recorded position or can vary itfrom the recorded position, as circumstances require, following whichthe string S is lowered without rotation, causing the shoe to be engagedin the seat or counterbore 2b where it is tightly engaged or wedged in amanner such as is indicated in Fig. 3 of the drawings.

With the shoe seated in the counterbore 2t circulation isre-established, causing the core 67 to be lowered and the loci; bolt 61retracted, thus freeing the sub for rotation in the sleeve. With the suband sleeve thus freed for relative rotation the string S can be turnedor rotated in the manner common to drilling with the rotary method, andpressure can be imparted to the bit with the result that the counterboreis deepened or extended, as indicated in Fig. 4 of the drawings, tobecome, in elfect, an extension of the bore W inclined or at an anglerelative thereto as a result of the guiding or deflecting action ofguide surface 23 of the shoe The keys on the shoe embedded in the wallof the extended bore leave slight grooves 150 therein, as indicated inPig. 4, and they serve to hold the shoe against turning as the bitoperates to advance the counterbore.

When the desired extension of the bore has been established the string Scan be withdrawn, in the course of which operation the bit can be keptin operation, and when the bit is out of the bore extension orcounterbore the string can be removed from the well, carrying the toolwith it.

The extended bore thus formed may, in practice, be but slightly smallerthan the initial or original bore W, and it is important to observe thatit is wholly free of obstructions or undesirable equipment such aswhipstocks, or the like.

If desired, the extension of the bore can be enlarged to correspond insize to the original bore by operating a string S with a suitable bit A,either alone or equipped with a reamer R, as circumstances require. Theenlargemerit of the extension or counterbore is illustrated in Fig. 5 ofthe drawings.

At any time in the course of operating the apparatus when the bit issuitably elevated oil bottom, if the instrument employed in the courseof orientation is lowered to assume the position shown in Figs. 2, 21and 26, and the string is then lifted without the lowering of the liquidlevel therein, the operator knows that the lock means of the shoe isengaged and the shoe at that time is in a predetermined rotativeposition relative to the string. If the instrument has been released forlowering into the position just mentioned and is not seated, and liftingof the string is accompanied by lowering of the liquid level therein,the operator knows that the instrument has not lowered to stop dischargeof liquid and this is probably due to the shoe lock being disengaged.

In the embodiment of the invention illustrated in Figs. 20 to 24,inclusive, the drilling string S is provided at its lower end with a bitA having a shoe B cooperatively related thereto as hereinabovedescribed. In this form of the invention a hole opening mechanism orreamer R is combined with or cooperatively related to bit A and islocated in or on the string S. In the particular case illustrated, thereamer R is located on the lower end of string S so that it occursbetween the string S and the sub on the bit A and is, therefore, aboveand immediately adjacent the bit A.

The reamer R is in the general nature of a reaming tool, that is, it isa tool having a body 200 carrying cutters 2191 and the cutters aresupported by body 200 so that they will cut or drill the formationpenetrated by bit A, so that the extension of the well bore made by bitA is enlarged an appreciable amount and, preferably, 50 that it iseither the size of the well bore 2% or is of a size slightly smallerthan the bore 205.

It is contemplated that in practice the reamer R may be varied widely inform of construction. In the case illustrated in the drawings, reamer Ris of conventional construction and the body 200 has legs that carry aplurality of circumferentially spaced cutters 201 so that they projectdownwardly and radially outward, as clearly illus trated in thedrawings.

With the equipment just described the string S with the bit A and reamerR carried thereby is lowered into the well bore 205 and operated asshown in Fig. 20, so that the shoe B wedges against one side of thecounterbore 20 made by the bit A. The bit A depends a substantialdistance below the reamer R and far enough so that a counter bore orseat 20 may be established sufficient to carry out the orienting anddrilling operations hereinabove described, the operation illustrated inFig. 21 being comparable to the operation illustrated in Fig. 2. Fig. 21shows the bit and shoe removed from the counterbore and scoring 150,such as may be left by the shoe, is shown on or in the wall of thecounterbore.

After the orienting operation is executed, while the bit is out of thecounterbore, so that the shoe B is located in the desired rotativeposition, the bit A is returned to the counterbore 20, as shown in Fig.22. The shoe is wedged into the counterbore 26 at the desired locationand established grooves in the wall, as clearly illustrated in Fig. 22.The drill string is then rotated and advances as the extension of thebore is formed and as this deepening operation is carried out the bit Aadvances and the reamer R follows the bit, with the result that boreextension is established, as shown in Fig. 23 of the drawings. Since theshoe B wedges against the side of the hole adjacent the bit A andcontinues to do so as the hole is drilled, the hole or extension of thebore that results is somewhat curved rather than straight.

If the reamer R is of a size corresponding to the bore 205 of well W theextension formed by the bit A and reamer R in the manner just described,will correspond in size to the well bore 205 and will be, in eifect, acontinuation thereof deflected in a predetermined manner from the axisof the well bore. If, on the other hand, the reamer R is somewhatsmaller than the bore 205 as the bore 20 is advanced, as illustrated inFig. 23, the extension of the bore continuing from the bore 205 will besomewhat smaller than the bore 205. In this case, the operation of theequipment illustrated in Figs. 20 to 23, inclusive, is followed by theoperation of a drilling string S carrying a conventional bit A and areamer R. The conventional bit and reamer will advance in the extensionof the bore established by the bit A and reamer R'so that the extensionbecomes a full size continuation of the Well bore.

By employing the steps above described, a bit A of small size, say, forexample, in practice, a bit A for cutting a hole 7% inches in diameteris eifective for use in the course of drilling a well bore from thatsize up to, say, 12% inches in diameter, assuming, of course, that wherethe hole is to be of the maximum diameter the reamer R is used incombination with the bit A, and a conventional bit A and reamer R arerun in accordance with the steps illustrated in Figs. 20 to 24,inclusive.

In the case illustrated in Figs. 25 to 27, inclusive, equipment such asillustrated in Figs. 1 to 5, inclusive, is used, however the operationinstead of being a mere simple single deflection of the well bore is thedeflection of the well bore and a following correction or seconddeflection. In this case, as shown in Fig. 25, an extension of the Wellhow is drilled ahead of the well bore 205 in accordance with theprocedure illustrated in Figs. 1 to 4, inclusive. The scoring 150 of thewall of the counterbore is shown in Figs. 25, 26 and 27.

Assuming an extension to have been drilled to a position as shown inFig. 26, and assuming orienting operations or a survey is made at thispoint in the procedure, it may be found that the extension of the Wellbore is not that which is desired, due possibly to error in calculationor a change in program, or to any one-of several different factors. Insuch event the bit A, as provided by the invention, with the shoe Bcombined therewith, is operated, as shown in Fig. 27, after surveys andorientation have been carried out as hereinabove described, causing theextension to have an advanced portion 20 deflected to extend in thedesired manner. This can all be carried out without removal of theequipment from the well, since it is possible as a result of the presentinvention to set and release the shoe B relative to the bit A wheneverdesired, and as often as necessary.

The practical significance of the procedure just pointed out and whichis shown in Figs. 25 to 27, inclusive, will be appreciated when it isrealized that to execute such an operation with standard methods orordinary equipment, for instance, with whipstocking, would requirenumerous runs or return trips, complicated survey and orientingoperations, and it is doubtful whether it could be executed practicallyunder the most ideal conditions.

Having described only a typical preferred form and application of myinvention, I do not wish to be limited or restricted to the specificdetails herein set forth, but wish to reserve to myself any variationsor modifications that may appear to those skilled in theart and fallwithin the scope-of the following claims:

Having described my invention, I claim:

1. A well deflecting tool comprising a rotatable drill bit having alongitudinally extending axis of rotation, a bit guiding shoe having anexternal guide surface thereon, and means coupling said bit and saidshoe to each other 'for relative rotation about said axis with saidguide surface located in a fixed axial and radial relationship to saidaxis, said guide surface having a lower edge extending partially aroundthe circumference of said bit adja- 14 cent the lower end thereof, saidguide surface being inclined outwardly from said axis in a directionupwardly fromsaid'lower edge.

2. A well deflecting tool comprising a drill bit having a longitudinallyextending axis of rotation, 21 bit guiding shoe comprising an annularcylindrical sleeve, a guide portion depending from the lower end of saidsleeve and extending partially around the circumference of said bit,said portion having a cylindrically curved external surface inclineddownwardly and inwardly from said sleeve, and means coupling said bitand said sleeve to each other for relative rotation about said axis withsaid guide surface located in a fixed axial and radial relationship tosaid axis.

3. A well deflecting tool as recited claim 2 wherein a. plurality ofoutwardly projecting guide ribs are mounted upon said cylindricalsurface and extend longitudinally of said surface.

4. vA well deflecting tool as recited in claim 2 wherein saidcylindrical surface terminates in a lower edge located slightly abovethe lower end of said bit, said cylindrical surface being inclined tothe axis of rotation of said drill bit at an angle such that aprojection of said cylindrical surface toward the lower end of saiddrill bit intersects the outer circular peripheral path defined by saiddrill bit upon rotation about its axis.

'5. .A well deflecting tool as recited in claim 4 wherein the radius ofcurvature of said cylindrical surface is substantially equal to theradius of said circular peripheral path.

6. A well deflecting tool comprising a hollow tubular sub rotatableabout its longitudinal axis, a drill bit fixedly secured to the lowerend of said sub, a bit guiding shoe comprising a sleeve surrounding theexterior of said hollow tubular sub for rotation relative thereto,abutment means engageable between said shoe and said sub to maintainsaid shoe in fixed axial relationship with said bit during rotation ofsaid sub relative to said shoe, an external guide surface extendingdownwardly from said sleeve, said guide surface having a lower edgeextending partially around the circumference of said bit adjacent thelower end thereof, a fluid actuated piston reciprocable within saidhollow tubular su b between a first and a second position, a latchmember mounted upon said sub and engageable in a cooperating recess insaid sleeve, and means connecting said latch member to said piston forengaging said latch member in said recess when said piston is in saidfirst position and for retracting said latch member from said recesswhen said piston is in said second position, said external guide surfacebeing located in fixed radial relationship to the longitudinal axis ofsaid hollow tubular sub irrespective of whether said latch member isengaged in said recess or is retracted from said recess.

7. A Well deflecting tool comprising a hollow tubular sub rotatableabout its longitudinal axis, a drill bit secured to the lower end ofsaid sub, bit guiding means rotatably mounted upon said sub, a fluidactuated piston reciprocable within said hollow tubular sub between a.fi-rst and a second position, a latch member mounted upon said sub andengageable in a cooperating recess in said bit guiding means when saidbit guiding means is in a predetermined rotative position upon saidsu'b, means directly coupling said latch member to said piston operableto position said latch in said recess when said piston is in said firstposition and said recess is rotatively aligned with said latch and todisengage said latch and said bit guiding means when said piston is insaid second position, said piston having a longitudinally extendingpassageway therethrough for receiving a surveying instrument, and meansfor blocking said passageway against the passage of said instrument whensaid piston is in said second position.

8. A well deflecting tool as recited in claim 7 wherein said lastmentioned means comprises a member pivotally connected to the lower endof said piston at a location wherein said member may normally hang in aposition clear of said passageway, and an inclined surface on said bitadapted to cam said member into said passageway upon movement of saidpiston toward said second position.

9. A well deflecting tool as recited in claim 7 including means biasingsaid piston toward said first position, said piston being movable tosaid second position upon the application of fluid pressure thereto, andmeans responsive to application of fluid pressure to said piston forrestricting said passageway.

10. The combination with a well drilling bit having a bit guiding shoerotatably mounted thereon, means for latching said shoe to said bit at apredetermined rotative position, and means operatively associated withsaid shoe for establishing a localized magnetic field having a knownrelationship to said predetermined rotative position; of a surveyinginstrument comprising an elongate casing axially positioned within saidbit, cooperating means on said casing and said bit locating said casingat a known axial position within said bit, first indicating meansoperable when said casing is at said known axial position to indicatethe direction of the earths magnetic field with respect to a referencepoint within said instrument, and second indicating means comprising afirst and a second magnetized needle mounted for independent rotationwithin said casing at spaced axial locations upon a common pivotal axis,the axial spacing of said needles being such that the respectivemagnetic fields of said needles mutually attract said needles to assumeand maintain a first rotative orientation with respect to each other,said needles being so located within said casing as to lie within saidlocalized magnetic field when said casing is at said known axialposition to thereby indicate the direction of the magnetic field of saidmagnetic means with respect to a reference point within said instrument,the field of said magnetic means being of a strength sufiicient toovercome the mutual attraction of said needles and to force said needlesinto a second rotative orientation with respect to each other wherebythe rotative position of said shoe and the location of said casing atsaid known axial position may be simultaneously determined.

11. The combination with a well drilling bit having a bit guiding shoerotatably mounted thereon, means for latching said shoe to said bit at apredetermined rotative position, and means operatively associated withsaid shoe for establishing a localized magnetic field having a knownrelationship to said predetermined rotative position; of a surveyinginstrument comprising an elongate casing axially positioned within saidbit, cooperating means on said casing and said bit locating said casingat a known axial position within said bit, a first and a secondmagnetized needle mounted for independent rotation with said casing atspaced axial locations upon a common pivotal axis, the axial spacing ofsaid needles being such that the respective magnetic fields of saidneedles mutually attract said needles to assume and maintain a firstrotative orientation with respect to each other, said needles beinglocated within said casing to lie Within said localized magnetic fieldwhen said casing is at said known axial position to thereby indicate thedirection of the magnetic field of said magnetic means with respect to areference point within said instrument, the field of said magnetic meansbeing of a strength sufficient to overcome the mutual attraction of saidneedles and to force said needles into a second rotative orientationwith respect to each other whereby the rotative position of said shoeand the location of said casing at said known axial position may besimultaneously determined.

12. The method of extending a well bore in a predetermined directioncomprising the steps of lowering a drill bit having guide meansrotatably mounted thereon to the bottom of said bore, moving said drillbit relative to said guide means to form a seat for said guide means,raising said drill bit and said guide means from said seat, locking saidguide means against rotation relative to said bit, rotating said bit toorient said guide means to guide said bit in the desired direction,lowering said drill bit and said guide means to reseat said guide meanswithin said seat formed by said drill while said guide means is lockedagainst rotation relative to said bit, unlocking said guide means fromsaid bit and advancing said bit and said guide means to extend said borein the desired direction.

13. A well deflecting tool comprising a rotatable drill bit having alongitudinally extending axis of rotation, a bit guiding shoe having anexternal guide surface thereon, means mounting said shoe on said bit forrotation of said bit relative to said shoe about said axis while saidshoe is maintained in a fixed axial relationship to said bit, and meansreleasably coupling said bit and said shoe to each other, said bit andsaid shoe being rotatable together about said axis when coupled to eachother and said bit being rotatable relative to said shoe about said axiswhen said coupling means is released, and said guide surface beingspaced the same radial distance from said axis irrespective of whethersaid bit and said shoe are coupled to each other for rotation togetherabout said axis or said coupling means is released to permit said bit torotate relative to said shoe about said axis.

14. A well deflecting tool comprising a rotatable drill bit having alongitudinally extending axis of rotation, cutting elements mounted onthe lower end of said bit, a bit guiding shoe having an external guidesurface thereon, means coupling said bit and said shoe to each other topermit said bit to rotate relative to said shoe about said axis, andabutment means engageable between said shoe and said bit to maintainsaid shoe in fixed axial relationship with said bit during rotation ofsaid bit relative to said shoe, said guide surface having a lower edgeextending partially around the circumference of said b1t adjacent saidcutting elements and having an upper edge extending partially around thecircumference of said bit below the upper end of said bit.

15. A well deflecting tool comprising a rotatable drill bit having alongitudinally extending axis of rotation, cutting elements mounted onthe lower end of said bit, a bit guiding shoe mounted on said drill bit,said bit being rotatable relative to said shoe about said axis, andabutment means cooperable between said bit and said shoe to maintainsaid shoe in fixed axial relationship with said bit while said bit isrotating relative to said shoe, said shoe having an external guidesurface thereon extending partially around the circumference of said bitadjacent said cutting elements in fixed radial relationship to saidaxis.

16. A well deflecting tool comprising an elongated tubular sub rotatableabout its longitudinal axis, a drill bit secured to the lower end ofsaid sub for rotation therewith, a bit guiding shoe having an externalguide surface thereon extending partially around the circumference ofsaid bit adjacent the lower end of said bit, means coupling said sub andsaid shoe to each other for relative rotation about said axis, saidcoupling means including means for maintaining said guide surface infixed axial relationship to said bit during rotation of said bitrelative to said guide surface, and means located on said sub engageablewith cooperating means located on said shoe to latch said shoe to saidsub at a predetermined rotative position of said guide surface relativeto said sub.

17. A well deflecting tool comprising a rotatable drill bit having alongitudinally extending axis of rotation, said bit including cuttingelements mounted at the lower end thereof, a bit guiding shoe having anexternal guide surface thereon, said guide surface having an upper edgeextending partially around the circumference of said bit below the upperend of said bit and being inclined down- 1 7 wardly and inwardly of saidaxis from said upper edge to a lower edge located above the lower end ofthe cutting elements of said bit, and means mounting said shoe upon saidbit to permit said bit to rotate relative to said shoe about said axiswhile said shoe is maintained in fixed axial relationship to said bit.

18. A well deflecting tool as defined in claim 17 wherein said guidesurface is inclined with respect to said axis of rotation at an anglesuch that a downward projecttion of said guide surface intersects theouter circular peripheral path defined by the cutting elements of saiddrill bit upon rotation of said drill bit about said axis.

19. A well deflecting tool as defined in claim 18 wherein said guidesurface is a cylindrical surface having a radius of curvaturesubstantially equal to the radius of said outer circular peripheralpath.

References Cited in the file of this patent UNITED STATES PATENTS

